1. Field of the Invention
The present invention relates to a Radio-Frequency transceiver device, and more particularly to a RF transceiver device capable of reducing Specific Absorption Rate and keeping the antenna efficiency or structure.
2. Description of the Prior Art
A wireless communication device is equipped with an antenna to emit or receive radio waves, so as to exchange radio-frequency (RF) signals and access a wireless communication system. Radio waves are high-frequency sinusoidal signals, such that every country in the world standardizes the power of radio waves, mainly for preventing from affecting users and/or interfering operations of other wireless communication devices. For example, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) suggests the value of Specific Absorption Rate (SAR) shall not exceed 2.0 W/Kg, while the Federal Communications Commission (FCC) suggests the value of SAR shall not exceed 1.6 W/Kg. SAR represents the absorption rate of a living body unit per the power of electromagnetic waves in a normal electromagnetic radiation environment, taking W/Kg as a unit. Additionally, various communication products are applied to various environments, so that distance factor is further taken into consideration. For example, SAR of handset wireless communication device such as mobile device or smart phones needs to be verified when the distance between the handset wireless communication device and a human body is 20 cm.
As well known in the art, enhancing antenna efficiency and reducing SAR value are often contradictory, because enhancing antenna efficiency may increase radiating power which increases SAR value. In such a situation, how to keep the antenna efficiency and meanwhile reduce SAR value has become a target of the industry.